Cut the Wood, or Burn the Wood
- Heat, light and pressure all bring change in matter
- Cut a log into firewood and it is still wood, only smaller
- Burn that firewood and what is left is ash, smoke and gases
- Same wood, same heat, two completely different kinds of change
Presenter notes: Open with two things happening side by side. Melt a piece of ice in a spoon and hold a burnt matchstick up beside it. Ask the class what both of them have in common, and accept the answer that something changed. Then ask what is different, and let them struggle for a moment, because the honest answer is that the water can be frozen back and the matchstick cannot. Tell them that every change in matter they will ever meet falls into one of those two groups, that the book lists twelve characteristics to tell them apart, and that by the end of the period they will not need the list because one sentence will give them all twelve.